Refactor database layer: convert to DatabaseProvider class with initialization

pubspec.yaml

@@ -0,0 +1,21 @@
+name: family_safety_tracker
+description: A server app using the shelf package and Docker.
+version: 1.0.0
+# repository: https://github.com/my_org/my_repo
+
+environment:
+  sdk: ^3.10.1
+
+dependencies:
+  shelf: ^1.4.2
+  shelf_router: ^1.1.2
+  dart_jsonwebtoken: ^2.16.0
+  bcrypt: ^1.2.0
+  dotenv: ^4.1.0
+  postgres: ^3.5.10
+  uuid: ^4.5.0
+
+dev_dependencies:
+  http: ^1.2.2
+  lints: ^6.0.0
+  test: ^1.25.6